title: Comamonas testosteroni uses a chemoreceptor for tricarboxylic acid cycle intermediates to trigger chemotactic responses towards aromatic compounds.
abstract: Bacterial chemotaxis towards aromatic compounds has been frequently observed; however, knowledge of how bacteria sense aromatic compounds is limited. Comamonas testosteroni CNB-1 is able to grow on a range of aromatic compounds. This study investigated the chemotactic responses of CNB-1 to 10 aromatic compounds. We constructed a chemoreceptor-free, non-chemotactic mutant, CNB-1Δ20, by disruption of all 19 putative methyl-accepting chemotaxis proteins (MCPs) and the atypical chemoreceptor in strain CNB-1. Individual complementation revealed that a putative MCP (tagged MCP2201) was involved in triggering chemotaxis towards all 10 aromatic compounds. The recombinant sensory domain of MCP2201 did not bind to 3- or 4-hydroxybenzoate, protocatechuate, catechol, benzoate, vanillate and gentisate, but bound oxaloacetate, citrate, cis-aconitate, isocitrate, α-ketoglutarate, succinate, fumarate and malate. The mutant CNB-1ΔpmdF that lost the ability to metabolize 4-hydroxybenzoate and protocatechuate also lost its chemotactic response to these compounds, suggesting that taxis towards aromatic compounds is metabolism-dependent. Based on the ligand profile, we proposed that MCP2201 triggers taxis towards aromatic compounds by sensing TCA cycle intermediates. Our hypothesis was further supported by the finding that introduction of the previously characterized pseudomonad chemoreceptor (McpS) for TCA cycle intermediates into CNB-1Δ20 likewise triggered chemotaxis towards aromatic compounds.
authors.affiliation: State Key Laboratory of Microbial Resources, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Ni
authors.forename: Zhou
authors.initials: Z
authors.lastname: Huang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Fan
authors.forename: Cheng-Ying
authors.initials: CY
authors.lastname: Jiang
authors.forename: Shuang-Jiang
authors.initials: SJ
authors.lastname: Liu
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis; D002952:Citric Acid Cycle / Q000502:physiology*; D020604:Comamonas testosteroni / Q000502:physiology*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016680:Genome, Bacterial; D008293:Malates / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D009154:Mutation; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D008293:Malates; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011994:Recombinant Proteins; C030298:malic acid